Single material fabrication of multi-channel structures printing method and direct write printing needle used

Abstract

This invention relates to a direct-write printing needle used in a single-material multi-channel structure printing method, comprising a needle shell with a feed inlet and a discharge outlet at its coaxial ends. The outer wall of the feed inlet end of the needle shell has a threaded mounting surface. Inside the needle shell are an inner flow channel, coaxially aligned with the feed inlet, closed at the end opposite to the feed inlet, with discharge holes arrayed on its side. An outer flow channel encloses the inner flow channel, open at the end opposite to the feed inlet, forming the discharge outlet. The flow sequence of the slurry within the needle is: feed inlet, inner flow channel, outer flow channel. This invention proposes a needle-embedded core structure, with multiple discharge outlets located on the side wall of the core, evenly distributed to ensure similar extrusion pressure at each outlet, guaranteeing smooth material flow and obtaining extruded structures with single, multiple, or irregularly shaped holes.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a multi-channel structure printing method and the direct-write printing needle used therein. Background Technology

[0002] Currently, 3D printing technology mainly focuses on metallic, ceramic, and polymer materials; among them, 3D printing of polymer materials is usually carried out through thermal or photo-assisted processes. Direct Ink Writing (DIW) is a commonly used method for 3D printing, which can achieve additive manufacturing using thermosetting or photocurable 3D printing inks, and has been widely applied in fields such as microstructure forming and smart device fabrication.

[0003] The printing of hollow channels has always been a key application area for direct-write printing technology. Coaxial printhead-based 3D printing and electrospinning technologies have wide applications in bioengineering. In addition, direct-write printing technology also has extensive applications in ceramic and metal materials, and the printing of hollow channels in ceramic and metal materials based on coaxial printheads has a significant market potential in heat exchangers.

[0004] Currently, the hollow product extrusion structure used in the industry usually has a feed inlet designed on the side of the needle, and the overall outflow channel is usually conical or straight. When a conical shape is used, the cross-sectional area is smaller closer to the extrusion port. This structure causes the extrusion pressure to increase as the flow channel diameter changes from large to small, resulting in difficulty in slurry extrusion. If necessary, an adapter pipe needs to be connected to the feed point, which increases the overall volume. When the adapter pipe is added, there are bends in the flow channel, which also leads to difficulty in slurry extrusion.

[0005] In practical use, the above structure is only suitable for product extrusion with a single channel and for curing modes involving two or more materials. If only a single material is used for printing, there are problems such as difficulty in curing and easy collapse of the channel. Summary of the Invention

[0006] In response to the shortcomings of the existing production technology, the applicant provides a single-material preparation method for multi-channel structure printing and a direct-write printing needle, which changes the conventional sidewall feeding to core feeding. It is also suitable for single-material extrusion and can extrude products with multiple internal channels.

[0007] The technical solution adopted in this invention is as follows:

[0008] A direct-write printing needle used in a single-material multi-channel structure printing method includes a needle shell, with an inlet and an outlet at the coaxial ends of the needle shell, respectively. An installation thread is formed on the outer wall of the inlet end of the needle shell. The needle shell has the following internal features:

[0009] The inner flow channel is coaxially arranged with the feed inlet, and the end of the inner flow channel opposite to the feed inlet is closed. Discharge pipe holes are arrayed on the side of the inner flow channel.

[0010] The outer flow channel encloses the inner flow channel, and the end of the outer flow channel facing away from the feed inlet is open, forming the discharge outlet.

[0011] The slurry flows through the needle in the following order: inlet, inner channel, and outer channel.

[0012] As a further improvement to the above technical solution:

[0013] The needle housing has a core inside, and the core is hollow to form an inner flow channel; the discharge tube holes are opened on the side wall of the core, and the discharge tube holes are axially staggered.

[0014] The core and needle housing are integrated into one piece.

[0015] The closed end of the core is flush with the outlet of the outer flow channel.

[0016] There is at least one core, and each core has a discharge tube hole.

[0017] The main body of the core adopts a cylindrical structure, and the end of the core near the discharge port is set as a hollow cross-section of the part to be extruded.

[0018] A backflow gap is reserved between the closed end of the inner flow channel and the discharge pipe hole at the lowest position in the axial height.

[0019] A single-channel product printing method using a printing needle includes the following steps:

[0020] The dispersed slurry is placed in a syringe, centrifuged and defoamed, and then the needle for the single-channel product is screwed into the syringe through the mounting thread for installation.

[0021] Under pressure, the slurry flows from top to bottom, squeezed into the inner channel of the core through the inlet; then squeezed into the outer channel through the outlet hole on the side of the inner channel; finally squeezed out from the outlet to form a hollow tube with an inner diameter equal to the outer diameter of the core and an outer diameter equal to the inner wall diameter of the outer channel. After curing by light, the finished product is obtained.

[0022] The formula for the slurry used is as follows:

[0023]

[0024] A method for printing three-channel products using printing needles involves placing a well-dispersed slurry in a syringe, centrifuging to remove bubbles, and then screwing the needles for the three-channel products into the syringe via mounting threads.

[0025] Under pressure, the slurry flows from top to bottom, squeezed into the inner channel of the core through the inlet; then squeezed into the outer channel through the outlet hole on the side of the inner channel; finally squeezed out from the outlet to form a hollow tube with an inner diameter equal to the outer diameter of the core and an outer diameter equal to the inner wall diameter of the outer channel. After curing by light, the finished product is obtained.

[0026] The formula for the slurry used is as follows:

[0027]

[0028] As a further improvement to the above technical solution:

[0029] The slurry flows into the inner channel from the feed inlet, and after touching the closed end, it accumulates upwards until it is squeezed out from the discharge pipe hole.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention addresses the problems of existing coaxial printheads, which mostly use a co-extrusion method for core and shell materials, and where the shell material is mostly introduced from the side, resulting in high viscosity and difficulty in extrusion, and making it impossible to achieve two hollow channels and multi-channel printing. The invention proposes a needle-head structure with an internal core, where the discharge port is located on the side wall of the core, and multiple discharge ports are provided. The discharge ports are evenly distributed, so that the extrusion pressure of each discharge port tends to be similar, ensuring smooth material discharge from all points.

[0032] The hollow structure of this invention does not require core material for molding. It utilizes an internal core for molding and can be applied to the extrusion of hollow structures made of a single material, achieving the purpose of coaxial printing of a single material.

[0033] The overall needle of this invention has only one feed port, and there is no need to assemble adapters or other structures on the side, which greatly reduces the assembly size; however, the overall size is the same as that of ordinary needles on the market, which does not affect the compatibility of the needle with the equipment, and the use of threaded connection ensures simple assembly and accurate coaxiality.

[0034] This invention provides two flow channels: one inside the core and the other between the core and the outer wall of the needle. Both flow channels are vertically downward during extrusion, eliminating the abrupt change in material flow and thus avoiding extrusion difficulties caused by excessive material viscosity.

[0035] The core structure of the present invention can use a single core or multiple cores, and can obtain a hollow tube with irregularly shaped channels inside without affecting the extrusion efficiency.

[0036] Using the needle of this invention, since the extrusion pressure is reduced, it is theoretically possible to process slurries with higher viscosity than those used in conventional basic equipment, thus making it more widely applicable. Attached Figure Description

[0037] Figure 1This is a schematic diagram of the three-channel extrusion needle structure of the present invention.

[0038] Figure 2 This is a schematic diagram of the three-channel extrusion needle of the present invention from another perspective.

[0039] Figure 3 This is a top view of the three-channel extrusion needle of the present invention.

[0040] Figure 4 This is a cross-sectional view of the three-channel extrusion needle of the present invention.

[0041] Figure 5 for Figure 4 The enlarged view of part A is used to illustrate the core ejection structure.

[0042] Figure 6 This is a schematic diagram of the irregular channel extrusion needle structure of the present invention.

[0043] Figure 7 This is a schematic diagram of the irregular channel extrusion needle of the present invention from another perspective.

[0044] Figure 8 This is a top view of the irregular channel extrusion needle of the present invention.

[0045] Figure 9 This is a front view of the irregular channel extrusion needle of the present invention.

[0046] Figure 10 for Figure 9 BB cross-sectional view.

[0047] Figure 11 for Figure 9 CC section view.

[0048] The components include: 1. Needle housing; 2. Inner flow channel; 3. Core; 4. Outer flow channel; 5. Discharge tube hole;

[0049] 101. Feed inlet; 102. Discharge outlet; 103. Installation thread. Detailed Implementation

[0050] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0051] like Figures 1-11 As shown, the direct-write printing needle used in the single-material preparation multi-channel structure printing method of this embodiment includes a needle shell 1. The two coaxial ends of the needle shell 1 are a feed port 101 and a discharge port 102, respectively. An installation thread 103 is formed on the outer wall of the feed port 101 end of the needle shell 1. The needle shell 1 has the following features inside:

[0052] The inner flow channel 2 is coaxially arranged with the feed inlet 101. The end of the inner flow channel 2 opposite to the feed inlet 101 is closed. The discharge pipe holes 5 are arrayed on the side of the inner flow channel 2.

[0053] The outer flow channel 4 encloses the inner flow channel 2, and the outer flow channel 4 is open at one end away from the feed inlet 101, forming the discharge outlet 102.

[0054] The flow order of the slurry in the needle is as follows: inlet 101, inner channel 2, outer channel 4.

[0055] The needle housing 1 has a core 3 inside, and the core 3 is hollow to form an inner flow channel 2; the discharge tube hole 5 is opened on the side wall of the core 3, and the discharge tube holes 5 are axially staggered.

[0056] The core 3 and the needle housing 1 are integrated into one piece.

[0057] The closed end of the core 3 is flush with the outlet 102 of the outer flow channel 4.

[0058] There is at least one core 3, and each core 3 is provided with a discharge pipe hole 5.

[0059] The main body of the core 3 adopts a cylindrical structure, and the end of the core 3 near the discharge port 102 is set as a hollow cross-section of the part to be extruded.

[0060] A backflow gap is reserved between the closed end of the inner flow channel 2 and the discharge pipe hole 5 at the lowest position in the axial height.

[0061] The single-channel product printing method using a print head in this embodiment includes the following steps:

[0062] The dispersed slurry is placed in a syringe, centrifuged and defoamed, and then the needle for the single-channel product is screwed into the syringe through the installation thread 103 for installation.

[0063] Under pressure, the slurry flows from top to bottom and is squeezed into the inner channel 2 of the core 3 through the inlet 101; then it is squeezed into the outer channel 4 through the outlet 5 on the side of the inner channel 2; finally, it is squeezed out from the outlet 102 to form a hollow tube with an inner diameter equal to the outer diameter of the core 3 and an outer diameter equal to the inner wall diameter of the outer channel 4. The tube is then cured by light to obtain the finished product.

[0064] The formula for the slurry used is as follows:

[0065]

[0066] This embodiment utilizes a three-channel product printing method with printing needles. The dispersed slurry is placed in a syringe, centrifuged to remove bubbles, and then the needles for the three-channel product are screwed into the syringe via the mounting thread 103 for installation.

[0067] Under pressure, the slurry flows from top to bottom and is squeezed into the inner channel 2 of the core 3 through the inlet 101; then it is squeezed into the outer channel 4 through the outlet 5 on the side of the inner channel 2; finally, it is squeezed out from the outlet 102 to form a hollow tube with an inner diameter equal to the outer diameter of the core 3 and an outer diameter equal to the inner wall diameter of the outer channel 4. The tube is then cured by light to obtain the finished product.

[0068] The formula for the slurry used is as follows:

[0069]

[0070] The slurry flows into the inner channel 2 from the feed inlet 101, and after touching the closed end, it accumulates upward until it is squeezed out from the discharge pipe hole 5.

[0071] The specific structure and working principle of this invention are as follows:

[0072] like Figures 1-5 The diagram shown is a schematic of a needle structure for extruding products with three channels, provided by the present invention. Figures 6-11 This is a schematic diagram of a needle structure for extruding products with irregular cross-section channels, provided by the present invention.

[0073] Figures 1-5 This represents the type where the cross-section of core 3 remains constant; Figures 6-11 This represents a type where the core 3 is designed with an irregular shape near the discharge end, while the rest has a cylindrical cross-section. However, the two extrusion structures are similar in that they both have top feeding and discharge from the side wall of the core 3, thereby relieving the extrusion pressure at the discharge port 102.

[0074] like Figure 1 As shown, the top of the needle housing 1 is provided with an installation thread 103 for threaded connection with the syringe, so as to realize the detachable installation of the needle.

[0075] like Figure 2 and Figure 3 As shown, a flow channel is formed inside the needle housing 1, and an integral core 3 is set in the flow channel. The core 3 divides the flow channel into an inner flow channel 2 and an outer flow channel 4. The end of the core 3 near the discharge port 102 is a closed structure, and the cylindrical outer surface of the core 3 is provided with... Figure 4 , Figure 5 The discharge pipe hole 5 is shown. There is a gap between the bottom discharge pipe hole 5 and the bottom end of the core 3. This gap allows the slurry to be squeezed downward into the bottom of the core 3 first, and then overflow and flow out from the discharge pipe hole 5. This structure, together with the array of discharge pipe holes 5, makes the extrusion pressure at each discharge pipe hole 5 tend to be the same, ensuring the smooth extrusion of the slurry.

[0076] As an alternative to this extrusion method, the number of cores 3 can be changed to one core 3, two cores 3, four cores 3, etc., depending on actual needs.

[0077] like Figures 6-8 As shown, to extrude products with irregularly shaped cross-section channels, refer to the reference. Figures 9-11 The core 3 is configured with an irregularly shaped structure near the discharge port 102, which is identical to the hollow cross-section of the product. Furthermore, the lowest vertical discharge pipe hole 5 is located above the irregularly shaped section of the core 3. This ensures that when the slurry is extruded, it undergoes normal extrusion with minimal resistance. Only when it approaches the discharge port 102 does it experience the shaping effect of the irregularly shaped section, resulting in an irregularly shaped hollow portion of the extruded product.

[0078] Compared with existing technologies, this invention first changes the feeding direction, thereby altering the flow path of the slurry from a tortuous flow to a vertical flow. Gravity is no longer a factor hindering slurry extrusion but rather an aid to it. The slurry of this invention is uniformly extruded from the sidewall of the core 3, requiring far less extrusion force than conventional unidirectional extrusion with a tortuous structure, thus reducing the power requirements on the equipment. In the extrusion method provided by this invention, the hollow portion is already in a preparatory state before extrusion, meaning the slurry is initially formed with a hollow position, rather than breaking apart from the axis after the entire strip is extruded. This reduces the difficulty of forming while significantly improving the product yield. Therefore, this invention has broad application prospects.

[0079] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A direct write printing needle for a single material, multi-channel structure printing method, comprising a needle housing (1), characterized in that: The needle housing (1) is formed using a built-in core (3). Its coaxial ends are an inlet (101) and an outlet (102), respectively. An installation thread (103) is formed on the outer wall of the inlet (101) end of the needle housing (1). The needle housing (1) has the following internal features: The inner flow channel (2) is coaxially arranged with the feed inlet (101). The end of the inner flow channel (2) away from the feed inlet (101) is closed. The discharge pipe holes (5) are arrayed on the side of the inner flow channel (2). An outer flow channel (4) encloses the inner flow channel (2). The outer flow channel (4) is open at one end away from the feed inlet (101), forming a discharge outlet (102). The flow order of the slurry within the needle is as follows: inlet (101), inner channel (2), outer channel (4). Multiple discharge pipe holes (5) are provided, and the extrusion pressure of each discharge pipe hole (5) tends to be similar. The inner flow channel (2) and the outer flow channel (4) are the flow channel inside the core and the discharge flow channel between the core and the outer wall of the needle, respectively. Both flow channels are vertically downward during extrusion. The core (3) and the needle shell (1) are integrally formed; The core (3) has two, three or four cores, and each core (3) has a discharge pipe hole (5).

2. The direct-write printing needle for a single-material fabrication of multi-channel structure printing method according to claim 1, characterized in that: The needle housing (1) is provided with a core (3), and the core (3) is hollow to form an inner flow channel (2); the discharge pipe hole (5) is opened on the side wall of the core (3), and the discharge pipe holes (5) are axially staggered.

3. The direct-write printing needle for a single-material fabrication of multi-channel structure printing method according to claim 2, wherein: The closed end of the core (3) is flush with the outlet (102) of the outer flow channel (4).

4. The direct-write printing needle for a single-material fabrication of multi-channel structure printing method according to claim 2, wherein: The main body of the core (3) adopts a cylindrical structure, and the end of the core (3) near the discharge port (102) is set as a hollow cross-section of the part to be extruded.

5. The direct-write printing needle for a single-material fabrication of multi-channel structure printing method according to claim 1, wherein: A backflow gap is reserved between the closed end of the inner flow channel (2) and the discharge pipe hole (5) at the lowest position in the axial height.

6. A three-pass product printing method using the print needle of claim 1, characterized by: The dispersed slurry was placed in a syringe, centrifuged and defoamed, and then the needles used for the three-channel product were screwed into the syringe through the installation thread (103) for installation. Under pressure, the slurry flows from top to bottom and is squeezed into the inner channel (2) of the core (3) through the inlet (101); then it is squeezed into the outer channel (4) through the outlet (5) on the side of the inner channel (2); finally it is squeezed out from the outlet (102) to form a hollow tube with an inner diameter equal to the outer diameter of the core (3) and an outer diameter equal to the inner wall diameter of the outer channel (4). The tube is then cured by light to obtain the finished product. The formula for the slurry used is as follows: 80-90% metal or ceramic powder 1-5% of UV-cured resin Photoinitiator 0.1%-2% UV-curable monomers 0%-5% Upconversion materials 0%-5% Thermal initiator 0.1%-2%.

7. The printing method according to claim 6, wherein The slurry flows into the inner channel (2) from the feed inlet (101), and after touching the closed end, it accumulates upward until it is squeezed out from the discharge pipe (5).

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